A Proof-of-Concept for Safety Evaluation of Inhalation Exposure to Known Respiratory Irritants Using In Vitro and In...

Area of Science:

• Toxicology
• Inhalation Exposure Assessment
• Non-Animal Testing

Background:

• Growing demand for non-animal testing methods in safety assessment.
• Lack of defined methodologies for predicting local respiratory effects from irritant inhalation.
• Need for reliable in vitro and in silico models for respiratory safety.

Purpose of the Study:

• To present a concept for using in vitro and in silico methods for inhalation exposure safety assessment.
• To evaluate three in vitro systems representing upper and lower respiratory regions.
• To determine the human relevance of in vitro data using in silico modeling.

Main Methods:

• Exposed three in vitro respiratory models (MucilAir™, A549 cells, lung slices) to six irritants via liquid, aerosol, or vapor.
• Measured cytotoxicity, cytokine release, epithelial resistance, oxidative stress, and mitochondrial membrane potential over 24 hours.
• Utilized an in silico model to predict airway surface deposition and compare with in vitro effect levels.

Main Results:

• In vitro systems responded to respiratory irritants with measurable effects.
• In silico modeling simulated airborne concentrations relevant to human exposure thresholds.
• A margin of exposure greater than 100-fold was calculated between in vitro effects and simulated human exposure.

Conclusions:

• The study presents a foundational framework for non-animal inhalation exposure safety assessment.
• Combining in vitro and in silico assays offers a promising approach for predicting respiratory effects.
• Further research is needed to refine and validate these non-animal methods for regulatory use.